Biomining: There's Gold In Them Thar Plants

Gold rush miners might have been better off using plants to find gold rather than panning streams for the precious metal. Early prospectors in Europe used certain weeds as indicator plants that signaled the presence of metal ore. These weeds are the only plants that can thrive on soils with a high content of heavy metals. One such plant is alpine pennycress, Thlaspi caerulescens, a wild perennial herb found on zinc- and nickel-rich soils in many countries. This plant occurs in alpine areas of Central Europe as well as in the Rocky Mountains. Most varieties grow only 8 to 12 inches high and have small, white flowers.

Biomining is the use of plants to mine valuable heavy metal minerals from contaminated or mineralized soils. In fact, 25% of all copper is mined this way, amounting to $1 billion in revenue annually. This ranks it as one of the most important applications of biotechnology today. Bioprocessing is also being used to economically extract gold from very low grade, sulfidic gold ores, once thought to be worthless.

To increase the efficiency of biomining, the search is on for bacterial strains that are better suited to large-scale operations. Bioprocessing releases a great deal of heat, and this can slow down or kill the bacteria currently being used. Researchers are turning to heat-loving thermophilic bacteria found in hot springs and around oceanic vents to solve this problem. These bacteria thrive in temperatures up to 100 degrees Celsius or higher and could function in a high temperature oxidative environment.